OldNovaGuy

Hmmm...this reminds me of the old days when we took 327 blocks and put 283 cranks in them with the L79 cam and built 302s.

So, anybody got any of these pieces cause all I got is the heads and a 5.3.

BigTex

iTrader: (16)

I'm sure you can find a 4.8 crank pretty easily for pretty cheap. Used 6L bare blocks can be had for a couple hundred. That would make a nice "327", but I'd sure hate to give up that extra 40 cubic inches.

I got it! Take a standard 6L block, bore out to 4.020 then add an Eagle 3.9" stroker crank. You'd get exactly 396 cubic inches and would make a ton more torque and power. Think 450 rwhp and tq compared to 350 of the 327. That sounds perfect for a classic nova.

http://cgi.ebay.com/ebaymotors/ws/eB...spagename=WDVW

ktmrider

Boy, the possibilities are endless! OldNovaGuy, you can now have your HO 396 "big" block cubes instead of the 327 small block.
OK, now are you more or less confused?!? The advice is solid and plentiful.

Andy1

Big Tex,

Do you happen to know if the parts will actually interchange? Will the crank fit? Use the 4.8 rods (nice and long)? Do you happen to know what the combustion chamber volumes are of the stock 4.8 & 5.3 heads? Can you direct me to some of this kind of fundamental info regarding mixing these parts? Lots of questions, I know, but any help is greatly appreciated. Thanks!!

Andy

BiggerJ

I am thinking about doing the same thing to my LS1. I want to take a stock LR4(4.8L) crank, and connecting rods and use my stock pistons. That would put me at a 312ci motor with a ~9.1:1 CR(ready for boost). If I wanted to stay NA I would likely switch the heads to LS6's to get the CR up to ~10:1. This way the parts are cheap and available. Anyone know what the limits of the LR4 rotating assembly are? I would like to spin the motor to 7-8k. I know the valvetrain would also have to be lightened/strengthend to get up there.

Sport Side

iTrader: (6)

Bigger J,

The only thing is your intake wont support that high of an rpm. Also, you'd have a very narrow powerband. You'd probably wanna think about one of those carb setups with the single/dual planes to spin the motor past 7k.

It would probably be a total track setup because you'd need a high stall converter to feed you into the desired power band.

BiggerJ

NA would be tricky at high rpms considering that the cam would probably also have to be optimized for high rpm. I figure I could use a turbo to make up for the stock LS1 intake/cam deficiencies. The LS6 or LS2 intake might give me some additional headroom.

I have a 6spd so, I would have to put shorter gears in the rear to get my rpms up quickly.

Intake/Exhaust flow aside do you think the LR4 rotating assembly can handle 7-8k at modest torque (~400lb-ft)?

Andy1

If you go stricktly by the calculations, an LS1 (346cu in) needs about 550 CFM @ 6500 RPM. The 312 cu in that BiggerJ talks about would need about 575 CFM @ 7500 RPM, so they're fairly close (using same constant for both). If he were to add the LS6 heads and intake, I would think he'd be in good shape.

BiggerJ, I'd advise you check for any required balancing of the rotating assembly when mixing parts. Any motor builders out there?

Andy

BiggerJ

Kinda neglected that part. Does anyone know the difference in weight between the 4.8 vs 5.7 pistons? Since this is the only difference in the rotating assembly, would this difference in weight matter?(my guess is yes) Maybe custom pistons to match the 4.8's weight would be the easiest solution(I'd rather stay cheap). How expensive is it to get a stock crank rebalanced?

Andy1

Keep in mind. that the 4.8 rod is longer than the 5.7 (the longest of all the L motors, AFAIK), and probably weights more. The extra length is good for the rod ratio. Couple that with the bob weight of the piston, and therein lies the answer. You should probably direct your question(s) to a knowleagable L motor balance shop........and share the answers with us, of course!

Andy